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प्रश्न
Using Huygens's construction of secondary wavelets explain how a diffraction pattern is obtained on a screen due to a narrow slit on which a monochromatic beam of light is incident normally.
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उत्तर
Consider a parallel beam of light from a lens falling on a slit AB. As diffraction occurs, the pattern is focused on the screen with the help of lens L2. We will obtain a diffraction pattern that is a central maximum at the centre O, flanked by a number of dark and bright fringes called secondary maxima and minima.
Each point on the plane wave front AB sends out secondary wavelets in all directions. The waves from points equidistant from the centre C, lying on the upper and lower half, reach point O with zero path difference and, hence, reinforce each other producing maximum intensity at point O.
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संबंधित प्रश्न
On the basis of Huygens' wave theory of light prove that velocity of light in a rarer medium is greater than velocity of light in a denser medium.
What is the shape of the wavefront in the following case?
The portion of the wavefront of light from a distant star was intercepted by the Earth.
Consider a plane wave front incident on a thin convex lens. Draw a proper diagram to show how the incident wave front traverses through the lens and after refraction focusses on the focal point of the lens, giving the shape of the emergent wave front.
Using this principle draw a diagram to show how a plane wave front incident at the interface of the two media gets refracted when it propagates from a rarer to a denser medium. Hence verify Snell's law of refraction.
When the width of the slit is made double the original width, how would this affect the size and intensity of the central diffraction band?
Light waves travel in vacuum along the X-axis. Which of the following may represent the wave fronts?
What is the geometrical shape of the wavefront for:
- Light diverging from a point source?
- The pattern of wavefront of the light from a distant star intercepted by earth?
For light diverging from a point source ______.
- the wavefront is spherical.
- the intensity decreases in proportion to the distance squared.
- the wavefront is parabolic.
- the intensity at the wavefront does not depend on the distance.
Represent diagrammatically how the incident planar wavefronts of wavelength λ pass through an aperture of size d, when d is approximately equal to λ.
Represent diagrammatically how the incident planar wavefronts of wavelength λ pass through an aperture of size d, when d is approximately equal to λ.
